Synology NAS installing legacy Serviio package versions
serviio1.5-native-armv5tel.tar.xz
serviio1.5-native-armv7l.tar.xz
serviio1.5-native-armhfneon.tar.xz
serviio1.5-native-ppc.tar.xz
serviio1.5-native-i686.tar.xz
serviio1.5-native-i686-add.tar.xz (was needed for DSM 5.x on one very specific large rack-mount NAS I think - if FFmpeg won't run on i686 you need to unpack this file in /var/packages/Serviio/target/lib after installation
serviio1.5-native-i686evansport.tar.xz
serviio1.5-native-x64.tar.xz
The legacy package .spk files themselves can be found at http://packages.pcloadletter.co.uk/downloads/old
You can download these and install them manually in DSM Package Center.
Serviio 2.1 package for Synology NAS - with limited hardware transcoding support!